In recent years the use of a laser beam for pipe installation has become quite prevalent. Most of the devices extant are used for larger pipe, that is, greater than six inch pipe diameter. Moreover, many of the devices, while providing means for positioning the laser beam to a specific grade and elevation do not necessarily establish the beam at the axis of the pipe. To establish the coincidence of the axis of the beam and the pipe, the general procedure is to shift the pipe to a position that is adjudged by the eye to be in alignment with the center. Obviously such trial and error procedure is not very accurate. U.S. Pat. No. 4,916,817 is an example of prior art which has a solution for the problem. The essence of this invention is to use what is referred to as a laser target anchored at one end of the pipe. In general a laser will be started at one end of a pipe and will emit a beam that travels through the pipe and strikes a target plate formed of a dielectric sufficiently translucent to allow the point at which the beam strikes the plate to be visible from the opposite end. The plate is provided with a series of cross hatch marks which indicate the center of the target and the pipe is adjusted until the beam strikes the laser target's center. There is also a level on the target plate that assists in identifying alignment errors. Note also other examples of diverse laser target systems for pipes cited in column 1 of this patent. Another type of prior art for laying pipe, U.S. Pat. No. 3,742,581 makes use of two projected planes of light through the pipe so that each plane is either coplanar or parallel to the selected axis. There are also a number of patents that utilize mechanical self centering devices such as U.S. Pat. Nos. 1,448,528, 2,447,932, 3,822,478, 4,069,688 and 4,773,164. Besides being structurally distinct from the present invention, none is concerned with the use of laser beams. U.S. Pat. No. 2,323,039 does bear a structural resemblance to the present invention, although this patent refers to his device as a clamp whose purpose is to weld flanges to pipes with the clamp holding the flange plate secure when his jaw members engage the inner diameter of the pipe. The driving means is a crank with a screw having oppositely arranged threads with followers connected to the jaws through links for driving the jaws in opposite directions as the screw is rotated.
Accordingly it is an object of this invention to provide a simple and inexpensive self centering laser guide for laying pipe.
Another object of the invention is to provide a mechanical self centering device that is readily adapted for pipe that is six inches diameter or less.
Still another object of this invention is to provide a pipe axis laser guide that is accurate and does not depend on mere observation to determine the pipe axis.
A further object of the invention is to adapt the self centering lasering guide for installing and aligning independent structures such as pillow blocks for the installation of shaft bearings.
An additional object of this invention is to mount a saddle assembly with an inclination gauge about the circumference of the pipe to measure pipe inclination.